Document 1 (Published Japanese patent application H08-18900) discloses a technology which detects whether a viewer is present or not in front of a stream reproducing device and performs automatic recording of the stream while the viewer is not present.
More specifically, a television receiver disclosed by Document 1 possesses the structure shown in FIG. 21. In FIG. 21, a terrestrial broadcasting receiving antenna 201 receives a signal of a terrestrial broadcasting. A satellite broadcasting receiving antenna 202 receives a signal of satellite broadcasting. A signal input terminal 203 receives an externally-fed audio and video signal.
A receiving unit 204 consists of a channel selection tuner and a demodulator circuit. The receiving unit 204 performs a channel selection of a specific station from the broadcast wave which antennas 201 and 202 receive, demodulates the selected signal, and generates an audio and video signal. A signal processing circuit unit 205 performs processing for the audio and video signal fed from the receiving unit 204 or the signal input terminal 203, and outputs the processed signal to a signal control unit 206.
A recording and reproducing device unit 207 possesses a recording medium and performs recording and reproduction of an audio and video signal. The reproduced audio and video signal is outputted to the signal control unit 206.
A detection device unit 208 detects whether any viewer is present or not in front of the television receiver, and outputs the detection result to the signal control unit 206.
A display unit 210 displays an image by the video signal. A speaker unit 209 converts a sound signal into sound. Parts other than the antennas 201 and 202 are housed in one case as the television receiver.
When the television receiver is turned on and brought to the state ready to be viewed, the detection device unit 208 detects whether there is any viewer present in front of the television receiver, and outputs the detection result to the signal control unit 206.
While the signal control unit 206 is inputting the detection result indicating the presence of a viewer from the detection device unit 208, the signal control unit 206 does not allow a recording and reproducing device unit 207 to operate. However, when the detection result indicates that the viewer is gone, the signal control unit 206 instructs the recording and reproducing device unit 207 to record the audio and video signal which the viewer has been viewing.
Afterward, when the viewer returns in front of the television receiver and the detection device unit 208 detects that the viewer is present again, the signal control unit 206 instructs the recording and reproducing device 207 to stop recording and to reproduce the recorded audio and video signal. Thereby, the viewer can view the stream for the non-viewed period automatically.
However, in the prior art, unless the audio and video signal itself during the non-viewed period is automatically recorded by the recording and reproducing device unit 207, the viewer cannot view the stream for the non-viewed period later. Therefore, when the remaining recordable time of the recording and reproducing device unit 207 is few or almost zero, the viewer cannot view the stream for the non-viewed period later.
In a place such as a living room (the television receiver is often installed at such a place), people often come and go. In the prior art, when at least one viewer is staying in front of the television receiver, automatic recording during the non-viewed period is not performed. Thus, when a plurality of viewers come and go alternately, and different non-viewed periods exist, the prior art can not handle this situation at all. After all, each of the viewers needs to view the stream for the non-viewed period, by manually finding his/her own non-viewed period and performing troublesome operation such as rewinding and fast-forwarding. Therefore, the prior art has practical difficulty in meeting the theme of automatic viewing of the stream for the non-viewed period later on.